Then as it roared into the parking lot, he laid eyes on the motorcycle commissioned to honor his firefighter son and Lieutenant Ed Walsh, the victims in March’s fatal Back Bay fire.

The chopper’s shiny metal frame features a gas tank shaped in the logo of the New England Patriots, and the seal of the Boston Fire Department with the names of Lieutenant Edward J. Walsh Jr., 43, and firefighter Michael R. Kennedy, 33, above the words “Last Alarm 3/26/2014.”

Motorcycle enthusiasts gathered alongside firefighters and city officials Sunday at Florian Hall in Dorchester for the unveiling of an Orange County Choppers-designed motorbike that honors the firefighters killed in the March 26 fire.

The New England Patriots will hold a raffle for the bike and give it away at their final home game this year on Dec. 28. The $10 raffle tickets will go on sale Tuesday at nefc2014.com.

Proceeds will benefit the Metropolitan SWAT Officers Association and charities in the names of the fallen firefighters.

The motorcycle will be on display in Gillette Stadium this season as part of the New England Fitness Challenge, a 12-hour fund-raiser sponsoredby the SWAT Officers Association that begins Sept. 27, featuring teams of military and first-responders including police, fire, and emergency medical technicians.

A Patriots-themed bike was already being made for the fund-raiser, but officials decided to have it remade in the victims’ names after the fire.

Walsh and Kennedy died in a nine-alarm blaze on Beacon Street that had been propelled by 45-mile-per-hour gusts of wind.

Walsh was a 43-year-old married father of three young children. Kennedy had been a Marine sergeant who served in Iraq.

“Their sacrifice showed us the way of life and a dedication to community that nothing else can,” Mayor Martin J. Walsh said Sunday. “This is an awesome gift with a lot of meaning.”

Orange County Choppers founder Paul Teutul Sr. rode the chopper into the parking lot to applause, asking, “You like the bike?”

The bike features a flattened football for a saddle, chrome detailing, and a lustrous frame painted red, white, and blue.

A Boston Strong logo stretches across the battery compartment, which lies behind the 111-cubic-inch motor.

Men and women in leather vests, representing local motorcycle clubs, stood marveling at the one-of-a-kind chopper.

“I’d buy up all the raffle tickets if I could,” said 58-year-old Quinn Smith, a motorcycle rider who lives in the area. “It’s a lot of ingenuity. A tremendous amount of ingenuity.”

The younger Kennedy was a member of the American Infidels, a motorcycle club dedicated to supporting the military and its veterans.

“He would have probably wanted to hop on it and do a burnout, and then go for a ride,” said James Crosby, a friend of Kennedy and a founder of the Infidels.

Kennedy’s mother, Kathy Crosby-Bell, said her son was an avid Patriots fan who once dug out a seat to watch a game in the snow while his friends watched from home.

“To take 10 steps back after they’ve designed something and redesign the whole thing in honor of Michael and Ed, I mean that’s incredible,” she said.